French gene therapy start-up Vivet Therapeutics said on Thursday it had raised 37.5 million euros ($41 million) in an initial financing round, with backing from the venture arms of Swiss drugmakers Novartis and Roche .

Vivet, created last year in Paris with a wholly owned subsidiary in Spain, is focused on developing novel gene therapies for rare, inherited metabolic diseases.

Its lead programme VTX801, which is expected to enter clinical testing by the end of 2018, targets a condition called Wilson disease caused by a defective gene in liver cells that can require liver transplantation and is sometimes fatal.

Vivet has developed a next-generation AAV gene therapy technology designed to increase gene expression levels in the liver, while reducing the risk of undesirable immune system effects.

Gene therapy seeks to cure rare genetic diseases by offering a one-time fix of a faulty DNA. There is rising interest in the field, even though the Western world's first gene therapy for an ultra-rare condition is being pulled from the market due to lack demand.